Paper feeding device for image forming apparatus

ABSTRACT

An embodiment of the present invention relates to an image forming apparatus including: a control panel for designating a size of sheets fed by a paper feeding cassette; a sidewall motor that opens a front sidewall and a rear sidewall to the maximum when the paper feeding cassette is drawn out from an apparatus main body and slides the front sidewall and the rear sidewall to both side positions of the sheets of the designated size when the paper feeding cassette is inserted into the apparatus main body; and an end wall motor that opens an end wall to the maximum when the paper feeding cassette is drawn out from the apparatus main body and slides the end wall to a trailing end position of the sheets of the designated size when the paper feeding cassette is inserted into the apparatus main body.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromProvisional U.S. Application 61/026,681 filed on Feb. 6, 2008, theentire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a paper feeding device for an imageforming apparatus that stably feed sheets to an image forming unit of acopying machine or a multi-function peripheral.

BACKGROUND

There is a paper feeding cassette mounted on an image forming apparatusto feed sheets to an image forming unit. In this paper feeding cassette,both sides and trailing ends of sheets of various sizes are regulated byguides to prevent a tilt of the sheets.

In the paper feeding cassette in the past, after supplying sheets, anoperator manually moves the guides to regulating positions according toa size of the sheets.

However, in the apparatus in the past in which the guides are manuallymoved, after supplying sheets into the paper feeding cassette, in somecase, the operator forgets to move the guides or fails to move theguides to accurate regulating positions. When the sheets in the paperfeeding cassette are not accurately regulated, the sheets skew when thesheets are taken out from the paper feeding cassette. As a result, it islikely that an image quality is deteriorated and a sheet jam occurs.

Therefore, there is a demand for a paper feeding device for an imageforming apparatus that can surely move, when sheets are set in a paperfeeding cassette, guides to regulating positions according to a size ofthe sheets, prevent the sheets from skewing, prevent a sheet jam fromoccurring, and realize improvement of an image quality.

SUMMARY

According to an aspect of the present invention, an image quality isimproved through improvement of performance for feeding sheets to anapparatus main body and a sheet jam is prevent from occurring.

According to the aspect, there is provided a paper feeding device for animage forming apparatus including: a housing member that is insertedinto and removed from an apparatus main body and stores recording media;a guide member that is slidably provided in the housing member andregulates a feeding position of the recording media to an image formingunit; and a driving member that slides the guide member according to asize of the recording media when the housing member is inserted into theapparatus main body.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a copying machine according to a firstembodiment of the present invention;

FIG. 2 is a schematic top view of a paper feeding cassette according tothe first embodiment;

FIG. 3 is a schematic diagram for explaining driving of sidewalls and anend wall of the paper feeding cassette according to the firstembodiment;

FIG. 4 is a schematic top view of stop positions of the sidewalls andthe end wall of the paper feeding cassette according to the firstembodiment;

FIG. 5 is a schematic diagram for explaining supply of sheets into thepaper feeding cassette according to the first embodiment; and

FIG. 6 is a schematic top view of a paper feeding cassette according toa third embodiment of the present invention.

DETAILED DESCRIPTION

A first embodiment of the present invention is explained below.

FIG. 1 is a schematic diagram of a copying machine 1 as an image formingapparatus according to the first embodiment. The copying machine 1includes a scanner unit 13 that scans an image, a printer unit 14 thatforms an image, a paper feeding unit 21 as a paper feeding deviceincluding an upper paper feeding cassette 21 a, a lower paper feedingcassette 21 b, and a large capacity cassette 21 c for feeing sheets P asa recording medium, and a paper discharging unit 70 including a firsttray 71 and a second tray 72 for accumulating the sheets P dischargedfrom the printer unit 14 as an image forming unit. A control panel 102as an input unit supported by a pole 101 is provided in an apparatusmain body 11 that configures an outer hull of the copying machine 1. Amanual paper feeding unit 23 is provided on a side of the apparatus mainbody 11. A conveying path 40 for the sheets P is provided in a routeleading from the paper feeding unit 21 or the manual paper feeding unit23 to the paper discharging unit 70 through the printer unit 14 of thecopying machine 1.

The scanner unit 13 scans an object having image information(hereinafter referred to as original document) fed from an auto documentfeeder (ADF) 35 and capture the image information as image data. Afterthe scanner unit 13 finishes scanning the image information, the ADF 35discharges the original document to a document discharging unit 31.

The printer unit 14 forms, on the sheet P, an image corresponding toinputted image information or the image information scanned by thescanner unit 13. The printer unit 14 includes photoconductive drums 41,charging devices 48 that uniformly charge the photoconductive drums 41,an exposing device 42 that forms electrostatic latent images on thephotoconductive drums 41, developing devices 43 that develop theelectrostatic latent images formed on the photoconductive drums 41, anda transfer device 44 that transfers toner images developed on thephotoconductive drums 41 onto the sheets P of arbitrary sizes. Thetransfer device 44 includes a transfer belt 44 a and a secondarytransfer roller 44 b. The printer unit 14 further includes a fixingdevice 45 that fixes the toner images on the sheet P having the tonerimages transferred thereon by the transfer device 44. The fixing device45 includes a fixing roller 46 and a press roller 47.

The conveying path 40 includes conveying rollers 24 and registrationrollers 16 for feeding the sheet P taken out from the paper feeding unit21 or the manual paper feeding unit 23 by a pickup roller 22 to thetransfer device 44. The conveying path 40 conveys the sheet P having thefixed toner images to the paper discharging unit 70 through the transferdevice 44 and the fixing device 45.

The paper discharging unit 70 includes a paper discharging and conveyingpath 60 that discharges the sheet P to the first tray 71 or the secondtray 72 or reverses the sheet P. The paper discharging and conveyingpath 60 includes a lower conveying path 61 and an upper conveying path62. A first gate 63 divides the lower conveying path 61 and the upperconveying path 62. The lower conveying path 61 reaches the first tray 71through a first paper discharge roller 18. The upper conveying path 62includes a second conveying path 52 on an upper side and a thirdconveying path 53 on a lower side. A second gate 67 divides the secondconveying path 52 and the third conveying path 53.

The second conveying path 52 reaches the second tray 72 through a secondpaper discharge roller 19. The third conveying path 53 is a reversingand retracting path for the sheet P. The third conveying path 53includes a reversing and conveying roller 68. When a trailing end of thesheet P conveyed to the third conveying path 53 passes the first gate66, the reversing and conveying roller 68 rotates in the oppositedirection. The reversing and conveying roller 68 rotates in the oppositedirection to reversely convey the sheet P from the third conveying path53 in the direction of a circulating path 50. The circulating path 50feeds the sheet P to the transfer device 44 again.

The upper paper feeding cassette 21 a and the lower paper feedingcassette 21 b of the paper feeding unit 21 have the same structure. Asshown in FIG. 2, each of the upper paper feeding cassette 21 a and thelower paper feeding cassette 21 b includes a case 78 as a housing memberthat stores the various sheets P and is inserted into and removed fromthe apparatus main body 11 and a front sidewall 80 f and a rear sidewall80 r as side guide members that are slidably provided in the case 78 andregulate both sides of the various sheets P. Further, each of the upperpaper feeding cassette 21 a and the lower paper feeding cassette 21 bincludes an end wall 81 as an end guide member that is slidably providedin the case 78 and regulates trailing ends of the various sheets P. Thecase 78 can be drawn out to a front side relative to the apparatus mainbody 11. The case 78 has on a rear side thereof a connector 78 a forconnecting the case 78 to an upper input and output terminal 11 a or alower input and output terminal 11 b of the apparatus main body 11 whenthe case 78 is inserted into the apparatus main body 11. A tray-up sheetmetal 82 that supports the sheets P is provided on a bottom surface ofthe case 78.

The front sidewall 80 f and the rear sidewall 80 r slide in an arrow “m”direction or an arrow “n” direction along a guide shaft 78 b fixed tothe bottom surface of the case 78. The end wall 81 slides in an arrow“s” direction or an arrow “t” direction along a slit 78 c formed in thebottom surface of the case 78.

As shown in FIG. 3, a front ladder 83 f is provided in the frontsidewall 80 f. A rear ladder 83 r is provided in the rear sidewall 80 r.The front ladder 83 f and the rear ladder 83 r engage with a gear 87driven by a sidewall motor 86. The front ladder 83 f, the rear ladder 83r, the sidewall motor 86, and the gear 87 configure a driving member.When the gear 87 rotates in an arrow “v” direction, the front sidewall80 f is slid in the arrow “n” direction by the front ladder 83 f and therear sidewall 80 r is slid in the arrow “m” direction by the rear ladder83 r. When the gear 87 rotates in an arrow “w” direction, the frontsidewall 80 f is slid in the arrow “m” direction by the front ladder 83f and the rear sidewall 80 r is slid in the arrow “n” direction by therear ladder 83 r.

The end wall 81 is slid by an end wall driving mechanism 84 as a drivingmember. The end wall driving mechanism 84 includes a conveyor belt 88that reciprocatingly conveys the end wall 81 and an end wall motor 90that reciprocatingly rotates the conveyor belt 88. When the connector 78a is connected to the input and output terminal 11 a or the input andoutput terminal 11 b, the sidewall motor 86 and the end wall motor 90are connected to a CPU 110 that controls the entire copying machine 1.The sidewall motor 86 and the end wall motor 90 are controlled to bedriven by the CPU 110.

The paper feeding cassette 21 a or the paper feeding cassette 21 b isdrawn out from the apparatus main body 11 to disconnect the connector 78a from the input and output terminal 11 a or the input and outputterminal 11 b of the apparatus main body 11. The sidewall motor 86drives in the arrow “w” direction to slide the front sidewall 80 f inthe arrow “m” direction and open the front sidewall 80 f to the maximumand stops the front sidewall 80 f in a sheet supply position. Further,the sidewall motor 86 slides the rear sidewall 80 r in the arrow “n”direction to open the rear sidewall 80 r to the maximum and stops therear sidewall 80 r in a sheet supply position. When the front sidewall80 f and the rear sidewall 80 r are present in the sheet supplypositions, a distance between the sidewalls 80 f and 80 r is larger thanthe width of largest sheets stored in the paper feeding cassette 21 a or21 b.

When the connector 78 a is disconnected from the input and outputterminal 11 a of the apparatus main body 11, the end wall motor 90rotates the conveyor belt 88 in the arrow “t” direction and slides theend wall 81 in the arrow “t” direction. The end wall motor 90 opens theend wall 81 to the maximum and stops the end wall 81 in a sheet supplyposition on a rear end side of the case 78. When the end wall 81 ispresent in the sheet supply position, a distance from a distal end 78 dof the case 78 to the end wall 81 is larger than the length of thelargest sheets stored in the paper feeding cassette 21 a or 21 b.Opening the front sidewall 80 f, the rear sidewall 80 r, or the endsidewall 81 to the maximum, means the sidewall is opened to a slidelimit in the case 78.

When the paper feeding cassette 21 a or 21 b is inserted into theapparatus main body 11 and the connector 78 a is connected to the inputand output terminal 11 a of the apparatus main body 11, the sidewallmotor 86 drives in the arrow “v” direction to close the front sidewall80 f and the rear sidewall 80 r according to a size of sheets in thepaper feeding cassette 21 a or 21 b. When the number of revolutions ofthe sidewall motor 86 reaches the number of revolutions set according tothe size of the sheets in the paper feeding cassette 21 a or 21 b, thesidewall motor 86 stops the driving. When the sidewall motor 86 stops,the distance between the front sidewall 80 f and the rear sidewall 80 rcoincides with the width of the sheets stored in the paper feedingcassette 21 a or 21 b. The front sidewall 80 f and the rear sidewall 80r regulate both sides in the width direction of the sheets P in thepaper feeding cassette 21 a or 21 b.

When the connector 78 a is connected to the input and output terminal 11a of the apparatus main body 11, the end wall motor 90 rotates theconveyor belt 88 in the arrow “s” direction to slide the end wall 81 inthe arrow “s” direction and closes the end wall 81 according to the sizeof the sheets in the paper feeding cassette 21 a or 21 b. When thenumber of revolutions of the end wall motor 90 reaches the number ofrevolutions set according to the size of the sheets in the paper feedingcassette 21 a or 21 b, the end wall motor 90 stops the driving. When theend wall motor 90 stops, the end wall 81 regulates the trailing end ofthe sheets P in the paper feeding cassette 21 a or 21 b.

The control panel 102 includes a display unit 102 a and a keyboard 102b. The control panel 102 has an input function for inputting conditionsfor image formation by the copying machine 1, start of the imageformation, start of image scanning by the scanner unit 13, and the liketo the CPU 110. The control panel 102 has a display function and thelike for performing display of a confirmation screen for inputtedinformation and the like and display of a down state and the like of thecopying machine 1. The control panel 102 displays insertion and removalof the paper feeding cassettes 21 a and 21 b into and from the apparatusmain body 11. A user designates, on the control panel 102, sizes of thesheets P stored in the paper feeding cassettes 21 a and 21 b.

The user designates, on the control panel 102, a size of the sheets Pstored in the upper paper feeding cassette 21 a as, for example, the A4landscape size in the JIS standard. The CPU 110 outputs a signal forstoring the sheets P of the A4 landscape size in a correct position tothe upper input and output terminal 11 a. The sidewall motor 86 and theend wall motor 90 of the upper paper feeding cassette 21 a drive,according to the signal from the upper input and output terminal 11 a,to store the sheets P of the A4 landscape size in the correct positionin the case 78. The user designates, on the control panel 102, a size ofthe sheets P stored in the lower paper feeding cassette 21 b as, forexample, the A3 size in the JIS standard. The CPU 110 outputs a signalfor storing the sheets P of the A3 size in a correct position to thelower input and output terminal 11 b. The sidewall motor 86 and the endwall motor 90 of the lower paper feeding cassette 21 b drive, accordingto the signal from the lower input and output terminal 11 b, to storethe sheets P of the A3 size in the correct position in the case 78.

The user instructs, on the control panel 102, the copying machine 1 toform an image on the sheets P. The upper paper feeding cassette 21 astores, for example, the sheets P of the A4 landscape size in the JISstandard as shown in FIG. 4 according to the instruction from thecontrol panel 102. When the upper paper feeding cassette 21 a isinserted into the apparatus main body 11 (the connector 78 a isconnected to the upper input and output terminal 11 a), the sidewallmotor 86 drives and the front sidewall 80 f and the rear sidewall 80 rslide to positions for regulating both the sides of the sheets P andstop. The end wall motor 90 drives and the end wall 81 is slid to aposition for regulating the trailing end of the sheets P and stops(indicated by a solid line in FIG. 4). The lower paper feeding cassette21 b stores, for example, the sheets P of the A3 size in the JISstandard according to the instruction from the control panel 102.

According to the instruction for image formation, the charging device 48charges the photoconductive drum 41. The exposing device 42 outputsimage light (exposure light) corresponding to image data that should beformed as an image on the charged photoconductive drum 41. The exposingdevice 42 irradiates the exposure light on the photoconductive drum 41to form an electrostatic latent image corresponding to the exposurelight thereon. The electrostatic latent image formed on thephotoconductive drum 41 is developed with a toner by the developingdevice 43 and visualized. A toner image obtained by visualizing theelectrostatic latent image on the photoconductive drum 41 is transferredonto the sheet P by the transfer device 44. The sheet P is fed from thepaper feeding unit 21 or the manual paper feeding unit 23 and conveyedthrough the conveying path 40 and reaches the transfer device 44. Thetoner image transferred onto the sheet P is fixed on the sheet P by thefixing device 45. The sheet P having the toner image fixed thereon isconveyed to the paper discharging and conveying path 60. The sheet P isdischarged to the first tray 71 or the second tray 72 through the paperdischarging and conveying path 60 or conveyed to the transfer device 44again through the circulating path 50.

While the designated image formation is carried out, for example, if thesheets P in the upper paper feeding cassette 21 a are exhausted, thecontrol panel 102 displays, on the display panel 102 a, a message forurging supply of the sheets P into the upper paper feeding cassette 21a. For the supply of the sheets P, the user draws out the upper paperfeeding cassette 21 a from the apparatus main body 11. When the userdraws out the upper paper feeding cassette 21 a and disconnects theconnector 78 a of the case 78 from the upper input and output terminal11 a of the apparatus main body 11, the sidewall motor 86 drives in thearrow “w” direction. The front sidewall 80 f slides in the arrow “m”direction to a position indicated by a dotted line in FIG. 4. The rearsidewall 80 r slides in the arrow “n” direction to a position indicatedby a dotted line in FIG. 4. The front sidewall 80 f and the rearsidewall 80 r open to maximum positions. The end wall motor 90 rotatesthe conveyor belt 88 in the arrow “t” direction. The end wall 81 slidesin the arrow “t” direction to a position indicated by a dotted line inFIG. 4 and opens to a maximum position.

In a state in which the front sidewall 80 f, the rear sidewall 80 r, andthe end wall 81 are open to the maximum, the user supplies the sheets Pof the A4 size into the case 78 of the upper paper feeding cassette 21a. When the sheets P are supplied into the case 78, the sheets P may outof alignment as shown in FIG. 5. Even if some of the sheets P are notaligned, after supplying the sheets P into the case 78, the userdirectly inserts the upper paper feeding cassette 21 a into theapparatus main body 11.

When the user inserts the upper paper feeding cassette 21 a into theapparatus main body 11 and connects the connector 78 a of the case 78 tothe upper input and output terminal 11 a of the apparatus main body, thesidewall motor 86 drives in the arrow “v” direction. The front sidewall80 f and the rear sidewall 80 r slide from the maximum open state topositions for regulating both the sides of the sheets P of the A4landscape size and stops in a position indicated by a solid line in FIG.4. The sheets P that are not aligned during the supply into the case 78come into contact with the front sidewall 80 f and the rear sidewall 80r to be regulated on both the sides thereof. Both the sides of thesheets P in the case 78 are aligned in A4 landscape size positions.

When the user connects the connector 78 a of the case 78 to the upperinput and output terminal 11 a of the apparatus main body 11, the endwall motor 90 rotates the conveyor belt 88 in the arrow “s” direction.The end wall 81 slides from the maximum open state to a position forregulating the trailing end of the sheets P of the A4 landscape size andstops in a position indicated by a solid line in FIG. 4. The sheets Pthat are not aligned during the supply into the case 78 come intocontact with the end wall 81 to be regulated at the trailing endthereof. The trailing end of the sheets P in the case 78 is aligned inan A4 landscape size position. The out of alignment of the sheets P iscorrected in the upper paper feeding cassette 21 a. The sheets P aresupplied in a state aligned in a correct paper feeding position of theA4 landscape size.

When the user supplies the sheets P into the lower paper feedingcassette 21 b instructed to store the sheets P of the A3 size, the usersupplies the sheets P in the same manner as the supply of the sheets Pinto the upper paper feeding cassette 21 a. The user draws out the lowerpaper feeding cassette 21 b from the apparatus main body 11. When theuser disconnects the connector 78 a of the case 78 from the lower inputand output terminal 11 b of the apparatus main body 11, the sidewallmotor 86 is drove to slide the front sidewall 80 f and the rear sidewall80 r from positions for regulating the sheets P of the A3 size to themaximum open positions. The end wall motor 90 drives to slide the endwall 81 from a position for regulating the sheets P of the A3 size tothe maximum open position.

The user supplies the sheets P of the A3 size into the lower paperfeeding cassette 21 b. After supplying the sheets P, the user insertsthe lower paper feeding cassette 21 b into the apparatus main body 11.When the user connects the connector 78 a of the case 78 to the lowerinput and output terminal 11 b of the apparatus main body 11, thesidewall motor 86 is drove. The front sidewall 80 f and the rearsidewall 80 r slide from the maximum open state to positions forregulating both the ends of the sheets P of the A3 size and stop. Theend wall motor 90 is drove and the end wall 81 slides from the maximumopen state to a position for regulating the trailing end of the sheets Pof the A3 size and stops.

In a state in which the lower paper feeding cassette 21 b is inserted inthe apparatus main body 11, the front sidewall 80 f and the rearsidewall 80 r are in contact with both the sides of the sheets P of theA3 size. The sheets P that are not aligned during the supply areregulated on both the sides by the front sidewall 80 f and the rearsidewall 80 r. Both the sides are aligned in A3 size positions. The endwall 81 comes into contact with the trailing end of the sheets P. Thesheets P that are not aligned during the supply are regulated at thetrailing end thereof by the end wall 81. The trailing end is aligned inan A3 size position. In the lower paper feeding cassette 21 b, thesheets P are supplied in a correct paper feeding position of the A3size.

In this embodiment, a size of the sheet P designated by the user on thecontrol panel 102 is not limited. The size may be the B4 size in the JISstandard, the Legal size, the Letter size, or the Ledger size of the USstandard, or the like. When the user changes a size of the sheet P inthe paper feeding cassette 21 a or 21 b, the user selects the upperpaper feeding cassette 21 a or the lower paper feeding cassette 21 b onthe control panel 102. The user inputs a size of the sheets P fed fromthe selected paper feeding cassette 21 a or 21 b and determines thechange of the size, on the control panel 102. According to informationinputted on the control panel 102, the CPU 110 outputs a signal forstoring the sheets P of the changed size in a correct position to theupper input and output terminal 11 a or the lower input and outputterminal 11 b.

In this embodiment, the user disconnects the connector 78 a from theinput and output terminal 11 a or the input and output terminal 11 b ofthe apparatus main body 11 and opens the front sidewall 80 f, the rearsidewall 80 r, or the end sidewall 81 to the maximum. However, thepresent invention is not limited to this. The front sidewall 80 f, therear sidewall 80 r, or the end sidewall 81 may be opened in a range inwhich the user can easily supply the sheets P.

According to the first embodiment, in supplying the sheets P into thepaper feeding cassette 21 a or 21 b, the user draws out the upper paperfeeding cassette 21 a or the lower paper feeding cassette 21 b from theapparatus main body 11. Then, the sidewall motor 86 slides the frontsidewall 80 f and the rear sidewall 80 r to the maximum open positions.The end wall motor 90 slides the end wall 81 to the maximum openposition. When the user supplies the sheets P into the case 78, thefront sidewall 80 f, the rear sidewall 80 r, or the end wall 81 is notan obstacle. The user can easily supply the sheets P.

According to the first embodiment, the sheets P are supplied into thecase 78 and the upper paper feeding cassette 21 a or the lower paperfeeding cassette 21 b is inserted in the apparatus main body 11. Then,the sidewall motor 86 slides the front sidewall 80 f and the rearsidewall 80 r to positions corresponding to the width of the sizedesignated by the user on the control panel 102. The end wall motor 90slides the end wall 81 to a position corresponding to the trailing endof the sheets P of the size designated by the user on the control panel102. The out of alignment of the sheets P that occurs during the supplyis corrected by inserting the upper paper feeding cassette 21 a or thelower paper feeding cassette 21 b into the apparatus main body 11. Thesheets P can be stored in a correct paper feeding position. The paperfeeding cassette 21 a or 21 b can feed the sheets P in a properposition. It is possible to easily align the leading end of the sheets Pin the position of the registration rollers 16, prevent a positionalshift of an image due to the out of alignment of the sheet P, andimprove an image quality.

According to the first embodiment, after supplying the sheets P, theuser does not have to operate the front sidewall 80 f, the rear sidewall80 r, or the end wall 81. The user can easily supply the sheets P. Afterthe supply of the sheets P into the case 78, the user does not forget toreset the front sidewall 80 f, the rear sidewall 80 r, or the end wall81 to the position for regulating the sheets P. It is possible toprevent a paper jam due to the failure to reset the front sidewall 80 f,the rear sidewall 80 r, or the end wall 81.

According to the first embodiment, the user can change a size of thesheets P in the paper feeding cassette 21 a or 21 b on the control panel102. It is easy to change the size of the sheets P in the paper feedingcassette 21 a or 21 b.

A copying machine according to a second embodiment of the presentinvention is explained below. In the second embodiment, a size of sheetsstored in the paper feeding cassette in the first embodiment isdesignated for each of inserting positions in the apparatus main body(e.g., when the paper feeding cassette is inserted into an upper part ofthe apparatus main body, the size is designated as the A4 landscape sizeand, when the paper feeding cassette is inserted into a lower partthereof, the size is designated as the A3 size) Otherwise, the secondembodiment is the same as the first embodiment. Concerning componentssame as those in the first embodiment, the explanation in the firstembodiment applies in the second embodiment.

In the second embodiment, for example, the upper input and outputterminal 11 a of the apparatus main body 11 is controlled by the CPU 110and outputs a signal for always storing the sheets P of the A4 landscapesize in a correct position. The lower input and output terminal 11 b iscontrolled by the CPU 110 and outputs a signal for always storing thesheets P of the A3 size in a correct position.

When the sheets P in the upper paper feeding cassette 21 a or the lowerpaper feeding cassette 21 b are exhausted, for example, the displaypanel 102 a displays a message for urging supply of the sheets P. Tosupply the sheets P, the user draws out the upper paper feeding cassette21 a or the lower paper feeding cassette 21 b from the apparatus mainbody 11 according to the message. For example, when the user draws outthe upper paper feeding cassette 21 a and disconnects the connector 78 aof the case 78 from the upper input and output terminal 11 a of theapparatus main body 11, the front sidewall 80 f and the rear sidewall 80r are opened to the maximum positions by the sidewall motor 86. The endwall 81 is opened to the maximum position by the end wall motor 90.

The user supplies the sheets P of the A4 size into the case 78 of theupper paper feeding cassette 21 a. Even if some of the sheets P are notaligned in the case 78, the user directly inserts the upper paperfeeding cassette 21 a into the apparatus main body 11. When the userconnects the connector 78 a of the case 78 to the upper input and outputterminal 11 a of the apparatus main body, the front sidewall 80 f andthe rear sidewall 80 r are slid by the sidewall motor 86. The frontsidewall 80 f and the rear sidewall 80 r slide from the maximum openstate to the positions for regulating both the ends of the sheets P ofthe A4-landscape size and stop. Both the sides of the sheets P in thecase 78 are aligned in the A4 landscape size positions.

The end wall 81 is slid by the end wall motor 90. The end wall 81 slidesfrom the maximum open state to the position for regulating the trailingend of the sheets P of the A4 landscape size and stops. The trailing endof the sheets P in the case 78 is aligned in the A4 landscape sizeposition. The out of alignment of the sheets P is corrected in the upperpaper feeding cassette 21 a. The sheets P are stored in a state alignedin the correct paper feeding position of the A4 landscape size. Supplyof the sheets P into the lower paper feeding cassette 21 b is performedin the same manner as the supply of the sheets P into the upper paperfeeding cassette 21 a.

In the second embodiment, a size of the sheets P designated for each ofinserting positions in the apparatus main body 11 is not limited. Thesize of the sheets P for each of the inserting positions in theapparatus main body 11 is changed, for example, during maintenance by aserviceperson. An output signal from the upper input and output terminal11 a or the lower input and output terminal 11 b is changed during themaintenance.

According to the second embodiment, when the user supplies the sheets Pinto the case 78, the front sidewall 80 f, the rear sidewall 80 r, orthe end wall 81 are open to the maximum. The front sidewall 80 f, therear sidewall 80 r, or the end wall 81 is not an obstacle. The user caneasily supply the sheets P.

According to the second embodiment, after the supply of the sheets P,the out of alignment of the sheets P that occurs during the supply iscorrected by inserting the paper feeding cassette 21 a or 21 b into theapparatus main body 11. The sheets P can be stored in a correct paperfeeding position. The paper feeding cassette 21 a or 21 b can feed thesheets P in a proper position. It is possible to prevent a positionalshift of an image due to the out of alignment of the sheet P and improvean image quality.

According to the second embodiment, after the supply of the sheets P,the user does not forget to reset the front sidewall 80 f, the rearsidewall 80 r, or the end wall 81 to the position for regulating thesheets P. It is possible to prevent a paper jam due to the failure toreset the front sidewall 80 f, the rear sidewall 80 r, or the end wall81.

A copying machine according to a third embodiment of the presentinvention is explained below. In the third embodiment, a size of sheetsstored in the paper feeding cassette is detected and the guide member isslid in the first embodiment. Otherwise, the third embodiment is thesame as the first embodiment. Concerning components same as those in thefirst embodiment, the explanation in the first embodiment applies in thethird embodiment.

In the third embodiment, as shown in FIG. 6, for example, the rearsidewall 80 r and the end wall 81 respectively include a side pressuresensor 91 and an end pressure sensor 92 as detecting members on surfacesthat come into contact with the sheets P. The side pressure sensor 91 orthe end pressure sensor 92 detects pressure caused by the contact withthe sheets P on the rear sidewall 80 r or the end wall 81. Detectionresults of the side pressure sensor 91 and the end pressure sensor 92are inputted to the CPU 110 from the connector 78 a and the input andoutput terminals 11 a and 11 b.

A first photo-sensor 93 a and a second photo-sensor 93 b as detectingmembers that detect, for example, the rear sidewall 80 r are provided onthe bottom surface of the case 78. The first photo-sensor 93 a detectsthat the rear sidewall 80 r reaches the A4 landscape size position. Thesecond photo-sensor 93 b detects that the rear sidewall 80 r reaches theB4 size position.

Third to fifth photo-sensors 94 a, 94 b, and 94 c as detecting membersthat detect, for example, the end wall 81 are provided on the bottomsurface of the case 78. The third photo-sensor 94 a detects that the endwall 81 reaches the A4 landscape size position. The fourth photo-sensor94 b detects that the end wall 81 reaches the B4 size position. Thefifth photo-sensor 94 c detects that the end wall 81 reaches the A3 sizeposition. Detection results of the first to fifth photo-sensors 93 a, 93b, 94 a, 94 b, and 94 c are inputted to the CPU 110 from the connector78 a and the input and output terminals 11 a and 11 b.

The CPU 110 stores, in a memory 110 a, a pressure (α) caused on thefront sidewall 80 f and a pressure (β) caused on the end wall 81 when,for example, the sheets P in 500 sheet units are aligned in the case 78.The memory 110 a stores size of the sheets P correspond to driving timesof the sidewall motor 86, when a detection result (pressure) of the sidepressure sensor 91 run to the pressure (α). The memory 110 a stores sizeof the sheets P correspond to driving times of the end wall motor 90,when a detection result (pressure) of the end pressure sensor 92 run tothe pressure (β).

When the sheets P in the upper paper feeding cassette 21 a or the lowerpaper feeding cassette 21 b are exhausted, for example, the displaypanel 102 a displays a message for urging supply of the sheets P. Tosupply the sheets P, the user draws out the upper paper feeding cassette21 a or the lower paper feeding cassette 21 b from the apparatus mainbody 11 according to the message. For example, when the user draws outthe upper paper feeding cassette 21 a and disconnects the connector 78 aof the case 78 from the upper input and output terminal 11 a of theapparatus main body 11, the front sidewall 80 f and the rear sidewall 80r are opened to the maximum positions by the sidewall motor 86. The endwall 81 is opened to the maximum position by the end wall motor 90.

For example, the user supplies 500 pieces of the sheets P of the A4 sizeinto the upper paper feeding cassette 21 a. Even if some of the sheets Pare not aligned in the case 78, the user directly inserts the upperpaper feeding cassette 21 a into the apparatus main body 11. When theconnector 78 a of the case 78 is connected to the upper input and outputterminal 11 a of the apparatus main body 11, the front sidewall 80 f andthe rear sidewall 80 r are started to slide by the sidewall motor 86.When the rear sidewall 80 r slides in the arrow “m” direction from themaximum open state, the rear sidewall 80 r comes into contact with thesheets P. The side pressure sensor 91 inputs a detection result(pressure) caused by the contact with the sheets P to the CPU 110. TheCPU 110 detects the driving times of the sidewall motor 86, when adetection result of the side pressure sensor 91 coincide with thepressure (α). The CPU 110 reads a size of sheets correspond to thedriving times of the sidewall motor 86 in the memory 110 a.

When the user connects the connector 78 a of the case 78 to the upperinput and output terminal 11 a of the apparatus main body, the end wall81 is started to slide by the end wall motor 90. When the end wall 81slides in the arrow “s” direction from the maximum open state, the endwall 81 comes into contact with the trailing end of the sheets P. Theend pressure sensor 92 inputs a detection result (pressure) caused bythe contact with the sheets P to the CPU 110. The CPU 110 detects thedriving times of the end wall motor 90, when a detection result of theend pressure sensor 92 coincide with the pressure (β) The CPU 110 readsa size of sheets correspond to the driving times of the end wall motor90 in the memory 110 a.

The CPU 110 performs matching of the size of the sheets obtained fromthe detection result of the size pressure sensor 91 and the size of thesheets obtained from the detection result of the end pressure sensor 92and determines a size of the sheets P supplied into the case 78. Whenthe CPU 110 determines that the sheet size is the A4 landscape size, theCPU 110 stops the sidewall motor 86 according to detection of the rearsidewall 80 r by the first photo-sensor 93 a. The CPU 110 stops the endwall motor 90 according to detection of the end wall 81 by the thirdphoto-sensor 94 a.

In the case 78, the sheets P come into contact with the front sidewall80 f and the rear sidewall 80 r stopped in a detection position of thefirst photo-sensor 93 a and the end wall 81 stopped in a detectionposition of the third photo-sensor 94 a. The sheets P are regulated bythe front sidewall 80 f, the rear sidewall 80 r, and the end wall 81,whereby the out of alignment of the sheets P caused during the supply iscorrected. The sheets P are supplied in a state aligned in the correctpaper feeding position of the A4 landscape size in the upper paperfeeding cassette 21 a. Supply of the sheets P into the lower paperfeeding cassette 21 b is performed in the same manner as the supply ofthe sheets P into the upper paper feeding cassette 21 a.

In the third embodiment, a size of the sheets P supplied to the paperfeeding cassette 21 a or 21 b is not limited.

After the size of the sheets P is determined, a photo-sensor does nothave to be used for detection of a stop position of the front sidewall80 f, the rear sidewall 80 r, or the end wall 81. Driving times to thestop position of the sidewall motor 86 and the end wall motor 90corresponding to sizes of the sheets P may be set in advance todetermine the stop position of the front sidewall 80 f, the rearsidewall 80 r, or the end wall 81.

In the third embodiment, a size of the sheets P designated for each ofthe inserting positions of the apparatus main body 11 is not limited.When a size of the sheets P supplied into the paper feeding cassette 21a or 21 b is changed, the CPU 110 detects the driving times of thesidewall motor 86, when a detection result of the side pressure sensor91 coincide with the pressure (α) or the driving times of the end wallmotor 90, when a detection result of the end pressure sensor 92 coincidewith the pressure (β). The CPU 110 reads a size of sheets correspond tothe driving times of the sidewall motor 86 and the end wall motor 90.

According to a size of sheets, when the first or the secondphoto-sensors 93 a, 93 b detects the rear sidewall 80 r reaches theposition for regulating the sheets P, the CPU 110 stops the sidewallmotor 86. According to a size of sheets, when any one of the third tofifth photo-sensors 94 a, 94 b, and 94 c detects the end wall 81 reachesthe position for regulating the sheets P, the CPU 110 stops the end wallmotor 90. The front sidewall 80 f, the rear sidewall 80 r, or the endwall 81 can correct the out of alignment of the sheets P of a sizecorresponding to the size of the sheets and supply the sheets P into thepaper feeding cassette 21 a or 21 b in a state aligned in a correctpaper feeding position.

According to the third embodiment, when the user supplies the sheets Pinto the case 78, the front sidewall 80 f, the rear sidewall 80 r, orthe end wall 81 are open to the maximum. The front sidewall 80 f, therear sidewall 80 r, or the end wall 81 is not an obstacle. The user caneasily supply the sheets P.

According to the third embodiment, after the supply of the sheets P, theout of alignment of the sheets P that occurs during the supply iscorrected by inserting the paper feeding cassette 21 a or 21 b into theapparatus main body 11. The sheets P can be stored in a correct paperfeeding position. The paper feeding cassette 21 a or 21 b can feed thesheets P in a proper position. It is possible to prevent a positionalshift of an image due to the out of alignment of the sheet P and improvean image quality.

According to the third embodiment, after the supply of the sheets P, theuser does not forget to reset the front sidewall 80 f, the rear sidewall80 r, or the end wall 81 to the position for regulating the sheets P. Itis possible to prevent a paper jam due to the failure to reset the frontsidewall 80 f, the rear sidewall 80 r, or the end wall 81.

According to the third embodiment, it is possible to determine a size ofthe sheets P supplied into the case 78 using an output of the sidepressure sensor 91 and the end pressure sensor 92.

The present invention is not limited to the embodiments. Variousmodifications are possible without departing from the spirit of thepresent invention. For example, the number of paper feeding devicesmounted on and removed from the apparatus main body of the image formingapparatus and a size of recording media are not limited. A drivingsource on the apparatus main body side may be used for the drivingmember that slides the guide member. The image forming apparatus may bean image forming apparatus that forms an image on the basis of data froma computer terminal. A setting member may be an input unit of thecomputer terminal.

1. A paper feeding device for an image forming apparatus comprising: ahousing member that is inserted into and removed from an apparatus mainbody and stores recording media; a guide member that is slidablyprovided in the housing member and regulates a feeding position of therecording media to an image forming unit; and a driving member thatslides the guide member according to a size of the recording median whenthe housing member is inserted into the apparatus main body.
 2. Thedevice according to claim 1, further comprising a detecting member thatdetects the size of the recording media.
 3. The device according toclaim 2, wherein the detecting member includes a pressure sensor thatdetects pressure to the guide member by the recording media.
 4. Thedevice according to claim 2, wherein the detecting member includes aphoto-sensor.
 5. The device according to claim 1, wherein the size ofthe recording media is set by the apparatus main body.
 6. The deviceaccording to claim 5, wherein the size of the recording media is set bydata input by from the apparatus main body.
 7. The device according toclaim 5, wherein the size of the recording media is set according to aninserting position of the housing member into the apparatus main body.8. The device according to claim 1, wherein the driving member slidesthe guide member to an open position when the housing member is drawnout from the apparatus main body and slides the guide member to thefeeding position when the housing member is inserted into the apparatusmain body.
 9. The device according to claim 1, wherein the guide memberincludes a side guide member that regulates a side of the recordingmedia and an end guide member that regulates a trailing end of therecording media, and the driving member includes a first driving memberthat drives the side guide member and a second driving member thatdrives the end guide member.
 10. An image forming apparatus comprising:an apparatus main body including an image forming unit; and a paperfeeding device including a housing member that is inserted into andremoved from an apparatus main body and stores recording media to be fedto the image forming unit, a guide member that is slidably provided inthe housing member and regulates a feeding position of the recordingmedia to the image forming unit and a driving member that slides theguide member according to a size of the recording media when the housingmember is inserted into the apparatus main body.
 11. The apparatusaccording to claim 10, wherein the paper feeding device further includesa detecting member that detects the size of the recording media.
 12. Theapparatus according to claim 11, wherein the detecting member includes apressure sensor that detects pressure to the guide member by therecording media.
 13. The apparatus according to claim 11, wherein thedetecting member includes a photo-sensor.
 14. The apparatus according toclaim 10, wherein the apparatus main body further includes a settingmember that sets the size of the recording media.
 15. The apparatusaccording to claim 14, wherein the setting member includes an input unitthat inputs the size of the recording media.
 16. The apparatus accordingto claim 14, wherein the size of the recording media is set according toan inserting position of the paper feeding device into the apparatusmain body.
 17. The apparatus according to claim 10, wherein the drivingmember slides the guide member to an open position when the housingmember is drawn out from the apparatus main body and slides the guidemember to the feeding position when the housing member is inserted intothe apparatus main body.
 18. The apparatus according to claim 10,wherein the guide member includes a side guide member that regulates aside of the recording media and an end guide member that regulates atrailing end of the recording media, and the driving member includes afirst driving member that drives the side guide member and a seconddriving member that drives the end guide member.
 19. A sheet storingmethod for an image forming apparatus comprising: sliding a guide memberto an open position by drawing out a housing member from an apparatusmain body; and sliding the guide member to a storing position accordingto a size of a recording media by inserting the housing member into theapparatus main body.
 20. The method according to claim 19, wherein thesliding the guide member to the storing position includes sliding to astoring position at a side of the recording media and sliding to astoring position at a trailing end of the recording media.